The fridge in our 1987 TT finally gave up this summer.
What I did was purchase an all-electric fridge at Lowe's for about $210.00, and install an inverter ($125.00) in my truck to power it while on the road. Now I have a frost-free unit - only takes a couple of hours to be cold - no more frozen lettuce - ice cream is solid - my beer is chilled properly (most important).
This might not help out those that boon-dock, I don't in the trailer (too small holding tanks, no way to run a/c, etc etc.) --- I use the bus conversion if I'm going to boon-dock (100 gallon tanks, 8KW diesel gen, etc).
Fridge will run a long time on the truck battery system (4 batteries) with engine off - meaning I can "camp" at Wal*Mart overnight w/o any problem.
Just my $.02